Apparatus for coating



Patented Oct. 19, 1943 APPARATUS FOR COATING Edgar A. Lauring, International Falls, Minn, as-

signor, by mcsne assignments, to Minnesota and Ontario Paper Company, a corporation of Minnesota Application July 3, 1941, Serial No. 400,915

Claims.

This invention relates to a method of and apparatus for applying coating composition to vegetable fiber board and the like, and more particularly to a method of providing wallboard with smooth coated surfaces of pleasing appearance.

In the manufacture of certain kinds of fiberboard it is the practice to apply a layer or coating to the board, usually in the form of a fluid suspension of finely divided solid particles. Such coating compositions are well known and do not require description. However, it is ordinarily desirable to apply them in relatively concentrated form and to provide a substantially uniform and continuous layer.

It i an object of the present invention to provide a method of applying a coating to fiberboard and irregular shaped pieces of such board which shall be uniform in operation and easily controlled, and to produce a coated board or irregular shaped pieces of reliable and satisfactory quality. It is also an object to provide apparatus with which the method may be carried out automatically.

The method according to the present invention comprises briefly the step of applying a substantially continuous and more or less uniform layer of a fluid suspension of coating material upon the surface of a fiberboard, conducting the coated board through a suitable defined path, and directing jets of compressed air, disposed transversely of the board and in a direction opposite to its travel, at an angle thereto.

Other objects of theinvention will in 'part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such step with respect to each of the others, and the apparatus embodying features of construction, combination of elements and arrangement of parts, all as exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the following drawing in which:

Fig. 1 top plan view of the apparatus for carrying out the coating process,

Fig. 2 is a vertical section alon line 2-2 in Figure 1.

Fig. 3 is vertical section along line 3-3 in Figure 1.

The problem of applying coating material such as mixture, suspension or emulsions to surface of fiberboard, for'example, to apply coating material to moldings cut from fiberboard ha proved a matter of considerable difiiculty, particularly in instances wherein an especially irregular molding is to be coated.

In the method hereinafter set forth, the jets of air may be assisted by the force of gravity in removing surplus coating. The impact of the air jets forces the fluid coatin against the urface of the board intimate contact therewith. It also distributes the fluid coating composition uniformly over the surface of the board and removes any surplus coating without the formation of wavy surfaces.

In a typical instance of carrying out the invention, a board I9 is conveyed by means of a suitable conveyor which may be driven, rolls II which are mounted in the frame ill. The frame In is supported by uprights 35 which may be braced by cross members 36.

After the board has been coated it is carried to points of further treatment such as drying and storage by suitable conveyors, for example, driven rolls 34. These rolls 34 are mounted in a tablelike member.

A coating container is suitably supported by the feed table and the discharge table, and consists of a sloped bottom vessel 26 in the side near the upper edge thereof being mounted on rotatable rolls l3 for, supporting the board during the coating operation and moving the board along during the coating operation. The board is moved substantially continuously during the coating operation.

A substantially constant supply is maintained in vessel 26 during the coating operation. Container 30 receives its supply of coating material from a suitable source (not shown), and the coating material flows into vessel 26 until float 32 closes valve 3|. The coating material is taken from vessel 26 by pumps 21 which is preferably driven by a motor 28. The pump forces the coating material through conduit 28 to header member 20. Secured to header are a series of adjustable nozzles 2|. The coating material is applied to the board by the nozzle. The adjustability of the nozzles is highly important, particularly where irregular shaped surface is being coated.

astopermitthefloatfl toopenvalve ILooating material from vessel 30 is supplied by conduit 33 to the constantly circulating coating material.

To permit the coating oi varying width of fiberboard rail members I4 and II are arranged whereby easy adjustment is obtained. Rails it and II are held inplace by securing members ll passing through rails and holes l1.

After the board or other material has been covered with coating material the surplus-coating material is removed by compressed air jets. The air nozzles are carried by header member 22 and the nozzles ll are adjustable whereby the direction of the air jets can be controlled.

The material being coated is held securely against rail I! by spring tension members 24 and 2| carried by rail ll.

The air jets issuing from the nozzles extend transversely throughout the width or the board. The angle or impingement oi the jets is adjustable, and is oblique to the board in a direction opposed to the direction of the movement of the board. The eiiect oi the jets is to detain surplus coating material thereby giving a substantially uniform and even coating. The coated board is subsequently dried in a suitable dryer.

By adjusting the thickness velocity, and the angle at which the jets strike the board, it is found that the excess portion oi the coating material is wiped back and flows into the vessel 26. The initial thickness of the coating may be controlled by the applicator nozzles. The best results are obtained by. applying a surplus coating material and'removing the excess and at the same time the smoothing is accomplished. The thickness of the coating can be controlled by the velocity and/or direction of the air jets. By way of example, in operating the apparatus shown with the slot type of jet nozzles and directed at an angle of about 30 to 40 to the surface of the board gives satisfactory results. For varying the speed of the sheet other operating conditions must be varied accordingly.

What I claim is:

1. A coating apparatus for fiber board and the like comprising a container for coating material with one open side, a conveyor positioned in open side of said container for carrying board thereacross, coating nozzles positioned above said conveyor, pump means for withdrawing coating material from said container and discharging through said coating nozzles, adjustable air jet nozzles positioned above said conveyor and spaced apart from said coating nozzles, rail-like members positioned along the edges of said conveyor,

and spring means' on one of said rail-like members for holding the tlber board against other of said rails during coating operation.

2. A coating apparatus comprising a container for coating material with one open side, conveying means positioned in the open side or said container for carrying boards thereacross, coating nozzles positioned above said conveyor, means Ior withdrawing coating material from said container and discharging through said coating noszles, adjustable air jet nozzles positioned above said conveyor, rail-like members positioned along the edges of said conveyor, spring means secured to one or said rail-like members for holding boards being coated against the other rail-like member during travel over the said container.

3. A coating apparatus comprising a container for coating material, a second container for costing material for receiving coating material from said first container, means in said second container for opening supply line from first supply container whereby a constant supply or coating material is maintained in said second container, a conveying means positioned above said second container for moving board thereacross, coating nozzles positioned above said conveyor, pump means for withdrawing coating material from the second container and forcing through the coating nozzles, and nozzles for directing air jets against coated board for smoothing the coating and removing excess coating to said second container.

4. A coating apparatus for board, comprising a container for coating material with one open side, conveying means for carrying board across the open side of the container, means for supplying coating material to board on said conveying means, air jet means positioned above the conveying means for smoothing the coating material on the board, rail-like members positioned along the edges of said conveying means, and means on one'of said rail-like members for holding board being coated against the other rail-like member during travel ot the board over said container. 2

5. An apparatus for coatingboard, comprising a container for coating material with one open side, conveying means for carrying board across the open side of said container, means for supplying coating material to board on said conveying means; air jet means positioned above the conveying means for smoothing the coating material on the board, and adjustable guide means positioned along the edges of said conveying means.

EDGAR A. LAURING. 

